1. Field of the Invention
The present invention relates to a cylindrical jigsaw puzzle, and more particularly to an extendable cylindrical jigsaw puzzle.
2. Description of Related Art
After a common cylindrical jigsaw puzzle is completed, due to mutual combination between two adjacent arcuate puzzle pieces, the cylindrical jigsaw puzzle is able to stand on its own on a surface. However, because the overall structural relationship depends on the mutual complementarily arms and cutouts from two adjacent puzzle pieces, top edge and bottom edge of the cylindrical jigsaw puzzle are structurally weak because there is no support thereto such that when an impact is applied to the top edge and bottom edge, the cylindrical jigsaw puzzle is easily destroyed or damaged.
To overcome the shortcoming of the conventional cylindrical jigsaw puzzle, an improved cylindrical jigsaw puzzle is introduced to the market and has frames for the top edge and bottom edge of the cylindrical jigsaw puzzle so that the structural strength of the conventional cylindrical jigsaw puzzle is enhanced.
Having the frames for the top edge and bottom edge of the cylindrical jigsaw puzzle does increase the structural strength of the jigsaw puzzle, but the extension of the jigsaw puzzle is limited. That is, after the frames are added to the jigsaw puzzle, the jigsaw puzzle is not able to extend its application and thus the structure thereof is fixed. Should there be different requirements for the conventional cylindrical jigsaw puzzle, it is impossible for the conventional jigsaw puzzle to fulfill the requirements.
To overcome the shortcomings, the present invention tends to provide an improved cylindrical jigsaw puzzle to mitigate the aforementioned problems.